1. Field of the Invention
The present invention relates to the field of wireless communications; more particularly, the present invention relates to receiver diversity in a wireless communications system.
2. Related Art
FIG. 1 illustrates an exemplary network environment used today. Referring to FIG. 1, a corporate Local Area Network (LAN) backbone 102 interfaces to a number of desktop computers 1031-103n and may interface to Internet 101. Corporate LAN backbone 102 may comprise a firewall 102A, corporate server 102B, and a standard Ethernet switch 102C. Ethernet switch 102C includes an interface by which desktops 1031-103N are coupled to the corporate LAN backbone 102 and may access corporate sever 102B and Internet 101 (via firewall 102A).
More recently, Wireless LANs (WLANs) are being installed. Many of the recently implemented WLANs operate according to the protocol set forth in the 802.11 Standard, particularly as more enterprises are adopting the 802.11 Standard.
ISO/IEC DIS 802.11
FIG. 2 illustrates one embodiment of an 802.11 based WLAN (LAN) system. Referring to FIG. 2, the Internet or other LAN 201 is coupled to an 802.11 server 203 via firewall (FW) 202. Server 203 communicates with mobile stations in a number of 802.11 cells 2061-206N using an access point in each of cells 2061-206N, such as access point 204. Server 203 is coupled to access points such as access point 204, via an Ethernet connection. There is one access point for each of the 802.11 cells 2061-206N. Mobile stations in each of the 802.11 cells, such as laptops 2051 and 2052 in cell 2061, communicate wirelessly with the access points via the 802.11 protocol. The communications from mobile stations in the 802.11 cells to the access points are forwarded through to server 203 and potentially to Internet/LAN 201, while communications from Internet/LAN 201 are forwarded through server 203 to the mobile stations via the access points.
There are a number of problems associated with the current implementations of 802.11 networks. For example, in order to set up an 802.11 network such as shown in FIG. 2, a site survey is required in order to determine where each of the access points are placed to ensure that the 802.11 cells provide complete coverage over a particular geographic area. This may be costly. Also, the cost of each of the access points is approximately $500.00. Generally, such a high cost is a deterrent to having a large number of access points. However, by reducing the number of access points, coverage diminishes and the 802.11 network is less effective. Furthermore, there are a number of mobility problems associated with the current 802.11 network deployments. For example, the 802.11 standard sets forth a number of solutions to handle the issue of mobility of mobile stations between the 802.11 cells. However, these schemes do not work effectively as there is no standard solution in place and users haven't indicated a desire for long-term proprietary solutions.